Polishing machine



A ril 29, 1952 F. E. HENDRICKSON POLISHING MACHINE Filed NOV. 30, 1946 2 SHEETS-SHEET l \(llllllllllb) 4 E A TY A ril 29, 1952 F. E. HENDRICKSON 2,594,646

' POLISHING MACHINE I Filed Nov. so 1946 2 SHEETSSHEET2 AT 'y Patented Apr. 29, 1952 POLISHING MACHINE Fritz E. Hendrickson, South Elgin, Ill., assignoz of forty per cent to Bror G. Olving, Elgin, Ill.

Application November 30, 1946, Serial No. 713,277

2 Claims.

My invention relates to buning and polishing machines and particularly to automatic polishing machines.

An object of my invention is to provide a polishing machine having a work wheel which is pressed against the inside surface of a polishing belt by a spring biased slide.

Another object of my invention is to provide a polishing machine comprising a work wheel which is pressed against the inside surface of a polishing belt with a constant working pressure.

Another object of my invention is to provide a polishing machine embodying a plurality of work wheels of different hardness and of different pressures against the belt.

Other objects of my invention will either be apparent from a description of one form of a device embodying my invention or will be set out in the course of such description and be set forth in the appended claims.

In the drawings,

Figure 1 is a top plan view of a manual polishing machine comprising a single work wheel,

Fig. 2 is a front elevation of the parts shown in Fig. 1,

Fig. 3 is a fragmentary vertical sectional view taken on the line 33 of Fig. 1,

Fig. 4 is a view in side elevation of a polishing machine comprising three work wheels and an endless motor-driven belt for moving the work,

Fig. 5 is a bottom plan view of the parts shown in Fig. l, and,

Fig. 6 is a fragmentary sectional view through the three work wheels.

Referring first of all to Figs. 1 to 3 inclusive, I have there shown a polishing machine I l which comprises a base plate |3, which plate is substantially horizontal and which has secured thereto at one end thereof a vertical shaft electric motor 5, a plurality of securing bolts being provided for this purpose.

Atathe other end of the supporting plate l3 Iprovide an idling pulley I!) which is mounted on a vertical rotatable shaft 2|, this rotatable shaft being supported by a bearing member 23 which bearing is secured against base plate I3 by a plurality of bolts 25.

A polishing or abrasive belt 21 is adapted to operate over the motor pulley 29 and over pulley l9. Thedegree of coarseness of the belt 21 may be any desired value or it may be of a kind adapted to the work to be done and to the material which is to be polished.

. A single work wheel 3| which may be of the kindhereinbefore disclosed and claimed in my co-pending application #657,804 filed March 28, 1946, now abandoned, is mounted on a rotatable shaft 33, this rotatable shaft extended substantially parallel to the motor shaft and to shaft 2| and is supported by a movable bearing member 35, which bearing member may be moved in a substantially horizontal plane. Bearing member 35 is supported on base plate l3 as by a pair of bolts 31.

The bearing member 35 is moved as by a manually actuable screw-threaded shaft 39 which extends through a member 4|, which member may be secured to the'base plate l3 by a pair of bolts 43. Shaft 39 has its inner end abutting against a plate 45 which plate 45 is provided with two openings so that it may move on two guide shafts 41 and 49, these shafts being rigidly supported by a bracket member 5| and by member 4|. Springs 53 and 55 surround the guide shafts 4i and 49 respectively and extend from member 45 to bearing member 35 so as to permit of varying the pressure exerted by work wheel 3| against the inner surface of belt 21.

I have shown by broken lines in Fig. 1 of the drawings the position of work wheel 3 I, when the tension of the springs 53 and 55 has been reduced, thereby permitting the work wheel 3| to move rearwardly while subject to pressure from the endless belt enveloping said work wheel. The pressure between the work wheel 3| and belt 21 is relatively small when located as indicated by the broken line position and it is of course obvious that the turning movement of shaft 33 in a direction to compress springs 53 and 55 will move wheel 3| forwardly (as seen in Fig. l of the drawings) so as to vary or rather increase the pressure of the work wheel on the belt and therefore to also correspondingly increase the pressure of the belt against a piece of work.

Referring now to Figs. 4 to 6 inclusive, I have there shown a polishing machine 6| comprising a motor 33 having a pulley 35, a pulley El mounted on a rotatable shaft 69, which rotatable shaft is supported in a bearing H, which bearing is supported on a plate I3 by a, plurality of bolts 15. The motor 63 may be secured in proper operative position on plate 13 by a plurality of bolts 11.

I show three Work wheels 19, 8| and 83, placed side by side and embodying manually actuable externally screw-threaded adjusting shafts abutting against plates 81. Each of these plates is adapted to slide on two guide shafts 89 and 9i which extend from a member 93 to a member 95 and are rigidly held in their proper operative positions. Springs 91 and 99 encircle the guide shafts 89 and 9| respectively. The manipulation of the adjustment for work wheels 19, 8| and 83, in relation to the polishing belt, is similar to that for work wheel 3! of Fig. 1.

An endless polishing or abrasive belt it! is adapted to run over pulleys 61 and 65 and the three work wheels 19, 8| and 83 are adapted to engage the inner surface of the belt lfil. As shown in Fig. 4, the left hand work wheel 79 is subjected to greater spring pressure than work wheel SI, and work wheel 8! is subjected to greater spring pressure than work wheel 83.

The direction of movement of a piece of work N33 is from left to right as seen in Fig. l so that the degree of polishing will be such as to tend to remove the deeper scratches or marks first, as explained below. The work wheel 8!, with its reduced pressure against the belt Hll, will then remove the relatively coarse surface finish produced by work wheel '59, and work wheel 83 will produce a, still finer finish on the surface of a piece of work.

The successful operation of a machine embodying my invention in producing fine surface finish may be explained as follows: When a raw metal surface having deep scratches, pipes or pinholes is to be polished, it is necessary to first remove a sufficient amount of surface metal to reach the bottom of such scratches and blemishes. This is generally done by'the use of a coarse abrasive belt or wheel, which, however, produces another set of marks because of the coarseness of the abrasive and the amount of mechanical pressure applied. To remove the new grit marks produced by the first operation, the piece of work is then polished on orv by another abrasive wheel or belt having a finer grit and sometimes several subsequent operations on wheels or belts of successively finer grits are employed until a satisfactory finish is obtained. The theory back of this method of operation is that each successive wheel or belt will remove an amount of metal equal to the depth of the scratches produced by the prior operation and in so doing produces new and finer scratches which in turn are to be removed by further subsequent operations. For most, metal polishing, three abrasive operations are satisfactory, although. some parts may require six or seven operations with successively finer grits of abrasion.

During experimental work with my improved polishing machine I have found that different degrees of surface'finish can be obtained by varying the amount of mechanical contact pressure between the piece of work and the abrasive belt. For instance, when using a certain type of abrasive belt, if a high pressure was exerted between the belt and the piece of work to be polished, a relatively coarse type of surface finish was obtained and if a medium pressure was used a finer surface finish was obtained, and if a very light pressure was used a still finer type of surface finish was obtained. That this should be so may be clear when it is considered that the type or kind of finish obtained depends on the depth of scratches produced by the abrasive belt and that the depth of the scratches depends not only on the grade or fineness of the grit employed, but also upon the amount of mechanical pressure with which such grits are forced into contact with the piece of work being polished. By controlling the amount of pressure backing up the floating work wheel, the degree of polishing finish can thus be regulated.

scratches.

I have shown in Fig. 4 an endless work conveyor belt I95, the upper reach or span of which travels from left to right over two pulleys l0! and I09. Platforms Ill and H3 are provided, one at the left hand end of base T3 and the other at the right hand end of base 73, for reception and discharge respectively of the individual pieces of work to be polished.

Referring now to Fig. 6 of the drawings, I have there shown the three work wheels i9, 84 and 83 as being so constructed that they will inherently have different degrees of hardness. Thus work wheel 79 may be so designed and constructed that it will be relatively hard. Work wheel 8| may be so constructed that it will be of medium hardness, and work wheel 83 may be so constructed that it will be of minimum hardness, or soft.

The use of a spring-biased floating mounting for a work wheel, particularly on a manual type of polishing machine, insures that the mechanical pressure between the part or work to be polished and an abrasive or polishing belt is approximately constant and when employed in a non-automatic machine is independent of manipulation of a piece of work by the operator. The use of work wheels having relatively soft and resilient composition permits of yielding of the work wheel to the pressure of the work, permitting curved or irregular shaped surfaces of the work piece to sink into the body of the work wheel causing a pliable abrasive belt to envelope the surface of the work and closely hug the contour of the piece being polished.

This permits of obtaining a more uniform finish even when employing unskilled operators,

than has hitherto been obtained by skilled operators when using conventional sanding or polishing wheels. Thus, for instance, when flat surfaces are polished on a conventional sanding wheel the amount of pressure exerted by the operator on the work is extremely critical, too much pressure causing the abrasive grits to dig into the surface of the work and produce deep In my improved polishing machine the chance of exerting too much pressure has been entirely eliminated by the method of mounting the work wheel on a spring-biased floating slide so that the mechanical pressure between the work and the abrasive belt will remain substantially constant regardless of the manipulations and inadvertent movements of the operator.

Thus, referring to Figs. 1 to 3 of the drawings,

a the operator need only start in with light tension or pressure of the abrasive belt and tryout the pressure, increasing it in case it is not enough. He can do no damage to the work with too little pressure but will only have to repeat, with slightly increased pressure, his polishing of the work. After he has once determined the proper amount of pressure to be exerted by the kind of work wheel he has in his machine he can then continue and will obtain substantially the same results until wearing out of the abrasive belt occurs.

The work wheel thus floats under substantially constant pressure against the abrasive belt and to obtain the same kind of finish during successive operations it is necessary only for the operator to exert suflicient pressure on the work piece to make the work wheel float. Slight inadvertent movements of the polishers arms and hands during the actual polishing operation are thus unimportant as the chances of exerting too much pressure with the resulting deep scratches are entirely eliminated.

Referring to Figs. 4 to 6 inclusive, the piece of work I03 is first brought into pressure contact with the abrading surface of the belt just ahead of and below work wheel 79 and since work wheel 79 engages belt iill with the greatest mechanical pressure the deeper die marks or surface scratches are removed first. After that it again makes contact with the abrasive belt at the second work wheel 81 where a slightly finer polishing finish is obtained because of the smaller pressure exerted by the work wheel on the part being polished. A still finer and final polishing is imparted to the work by work wheel 83 because of the fact that the spring tension on work wheel 83 is much less than that on the preceding work wheels.

To obtain various finishes the individual work wheels may also be made of diiferent degrees of hardness, the first one being hard, the second being medium hard, and the third may be extremely soft. A combination of wheels of various hardnesses and different spring pressures also results in difierent types of finishes.

While I have shown three work wheels I do not desire to be limited thereto, the number of work wheels being made adjustable particularly when an endless conveying belt I05 is used to cause movement of the pieces of work past the different work wheels.

Depending on the type of finish desired, different grades of abrasive belts may be used. Thus, for instance, a first abrasive may be very coarse, or a belt having a finer grade of abrasive may be used, or a still finer grade of abrasive may be used.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and all such modifications coming within the appended claims are to be considered a part of my invention.

I claim as my invention:

1. An automatic polishing machine comprising in combination, an endless polishing belt, a plurality of belt-backing work wheels supported in contact with the inside surface of said belt, each said wheel being separately movable toward and away from the belt, means for moving a piece of work along said belt past each of said work wheels in succession, and biasing means for pressing said work wheels against said inside surface of said belt, said means being adjusted to urge each said work wheel against said belt with a greater force than the work wheel succeeding it in the direction of travel of a work piece.

2. The combination of claim 1 wherein each said work wheel is harder than the one succeeding it in said direction of travel of a work piece.

FRITZ E. HENDRICKSON.

E-QEFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 348,177 Totman Aug. 24, 1886 412,616 Hess Oct. 8, 1889 604,933 Graham May 31, 1898 1,030,473 Kroeze June 25, 1912 1,181,330 Mattison May 2, 1916 1,480,285 Moore Jan. 8, 1924 1,554,925 Showers Sept. 22, 1925 1,927,330 Williams Sept. 19, 1933 1,932,092 Etchart Oct. 24, 1933 1,936,991 Pinkney Nov. 28, 1933 2,071,034 Hanna Feb. 16, 1937 2,145,418 Herchenrider Jan. 31, 1939 2,279,783 Fowler Apr. 14, 1942 2,334,960 Roth et a1 Nov. 23, 1943 2,431,795 Elmes Dec. 2, 1947 FOREIGN PATENTS Number Country Date 1,734 Great Britain A. D. 1900 542,944 France May 24, 1922 562,871 Germany Oct. 29, 1932 

